Saturable reactor voltage regulation



y 1953 A. D. GILCHRIST 2,646,543

SATURABLE REACTOR VOLTAGE REGULATION Filed Sept. 30, 1950 2 Sheets-Sheetl mum a M, @M QQ, W, 6%

4rrM/vs ya 7 July 21, 1953 A. D. GILCHRIST 2,646,543

SATURABLE REACTOR VOLTAGE REGULATION Filed Sept. 50, 1950 2 Sheets-Sheet2 3 :mmm g 9 m 3 K a? Lt J0 J4 J2 if .77

Patented July 21, 1953 SATURABLE REACTOR VOLTAGE REGULATION Albert D.Gilchrist,'Lyndhurst, Ohio, 'assign'or-to The Leece-Neville Company,Cleveland, Ohio,

. a corporation'of'Ohio Application September 30, 1950, SerialNo.'18'7,740

- 12 Claims. 1

This invention'relates to control apparatus for alternating currentelectrical generating systems and, more particularly, to improvedcontrol apparatus for alternating current generating systems of thetype" used on motor vehicles for battery charging and other auxiliarypurposes and in which the speed of the alternator varies withthe'speedof thevehicledriving motor.

*-In"'the higher voltage battery charging sys- -'-te'rns,such-*as forcharging storage batteries of twelve to sixteen cells "or more, atroublesome problem-has always been present in regard to "obtainingalong operating life for the voltage regulators of-therelay or vibratorycontact type The used-with such'highe'r voltage systems. problemencountered resultsfrom the greater amountof energy required to becontrolled by -the-vibratory contacts of the voltage regulator. Thesehigher voltage systems usually require the use of a high'valueof controlresistance in par- 3 allel-with the contacts of the regulator and thisincreases the arc intensity at the contacts and,

"hence; increases the destructive effect on the contacts. H

' In the case of voltage'regulators of the double contact type used withsuch higher voltage battery systems, another problem is encountered duetoionization' oft-he gas present between the con- =tacts during"-transfer of the operating point of the'reg ulator from one' pair ofcontacts to the the other. 'Ihus'in a'situation where the voltageregulator is vibrating on the upper pair of con- .Lan'flarc. occursbetween the upper pair of con- ::tacts and maintains an I ionized paththerem between until the lower pair of contacts is closed, ii a' shortcircuit will occur through such ionized 2 math which may have adestructive efiect on the contacts. even to the extent of: causing thecontacts to bewelded together" into a solid mass.

I The present invention minimizes or eliminates these difliculties and,as its principal object, provides generator system control-means inwhichthe contacts of 'the' voltage .1 regulator, whether single or' multiplepairsf contacts andregard- -less of the'voltage ot the system,-are'required tocontrol onlyv airelatively small-amount of elec- 2 tricalenergy which will not be injurious to the contacts, andin whichsuch arelatively small amount of energyacting'through a saturable reactorincluded in the field excitation means of an alternator produces astrong regulating action on the'alternator.

Another'object of the'p'resent invention is to provide improved controlapparatus for a generating system in which the excitation means for thealternator field includes an auxiliaryrectifier and a saturable reactor;and'in' which the mag-- netizing or control'coil" means of the reactoris controlled by regulator means of the relay type which isautomatically responsiveto-the operat ing condition of the alternatorand in effect acts as a voltage sensing device.

Still anotherob-jectis -to""provide improved I generator control#apparatus "of the character tacts tocontrol the voltage of thegenerator 7 "while the-latter isoperating under heavy load and atmedium'speeds and the loadis dropped *suddenly,-'the regulatorthereupontransfers its operating point to the lower pair of contacts andcontinues to maintain the'voltage of the genera- ,:;.tor'at:its normalvalue. If, at the time of-this itransfer of theoperating pointof thevoltage "regulator from'one' pair of contacts to the other,

mentioned in which the regulator means consists of bothvo-ltage andcurrentregulators of the relay type.

A further-object is to provide improved generator control apparatus ofthekind above'referred to in which the field excitation means for thealternator includes" impedance "coil means of the-reactorandwhichimpedance coil means is located in the alternating currentportion of the field circuit.

Yet anotherobject is to provide'improved generator control apparatus ofthe character above indicated inwhich the alternator is a threephasealternator and the field excitation means for the alternator includes athree-phase rectifier and a saturable'reactor for each of thethree-phase alternating current portions of the *field circuit.

- As an additional object this invention provides control apparatus ofthe character mentioned in which the field excitation means for thealternator includes a saturable'reactor controlled by a v voltageregulator "oftherelay typeresponsive to the operating conditioriof thealternator, and in which the energization of the magnet coil means ofthe voltage regulator is controlled by a'voltage divider.

This invention can" be'further briefly summarized as consisting incertain novel combinations and arrangementsof parts hereinafterdescribed in detail and particularly set out in'the claims hereof.

r In the accompanying sheets of drawings,

Fig. 1'1s a-wiring diagramshowing generat- "ing -'system* controlapparatus embodying the present invention and inwhich a saturablereactor located in the alternating current portion of the field circuitof an alternator is controlled by regulator means of the relay typeresponsive to the operating condition of the alternator.

Fig. 2 is a. wiring diagram showing a generating system similar to thatof Fig. l but in which the voltage regulator of the regulator means isof the double contact type; and

Figs. 3 and 4 are wiring diagrams showing generating systems similar tothe generating systems of Figs. 1 and 2 respectively, but in which thesaturable reactor of the field excitation means is a three-phasesaturable reactor.

In the embodiment of the invention illustrated in Fig. 1, a generatingsystem I3 is shown comprising an alternator II which delivers currentthrough a main or power rectifier I2 to an external direct current loadhere represented by a storage battery I3 to be charged. The alternator II may be of the inductor type and is here shown as a three-phasealternator having star-connected inductor windings Ma, I 'ib and Hlc anda field winding I5. Th main rectifier I2 is a full wave three-phasebridge type rectifier which can be of the dry plate construction andcomprises circuit arms I211, i212 and [20 with which the respectiveinductor windings I ia, Mb and Me are connected by conductors extendingfrom the alternating current load terminals ita, I-Eb and H50 of thealternator. The rectifier [2 has direct current load terminals Ho andill) to which the storage battery I3, representing the external load, isconnected by the direct current load conductors I8a and [3b.

Th external direct current load circuit represented by the conductorsl8a and I8b is controlled by a load relay 2!! which, in accordance withone feature of the present invention, has a novel energizing circuitwhich will be presently described. This load relay may be of the typecomprising a magnet frame 2i including a core 22 carrying a magnet coil23 and a movable armature 2Q in cooperating relation to such frame andcore. The load relay 20 also includes normally open stationary andmovable switch contacts 25 and 26 in series relation to the loadconductor Iiib of the external direct current load circuit.

The magnet windings 23 of the load relay 20 is adapted to be energizedfrom the alternator Ii through an auxiliary rectifier 27 which is hereshown as being a three-phase full wave bridge type rectifier havingcircuit arms 21a, 27b and 210 and a pair of direct current loadterminals 28 and 29. The terminals of the magnet coil 23 are connectedwith the direct current terminals 25 and 29 by the conductors 30 and 3|.The circuit arms 27a, 23b and 210 of the auxiliary rectifier 2? areconnected respectively with the terminals Ifia, Ifib and I60 of thealternator II by the conductors 32, 33 and 34.

As an important feature of the present invention the improved generatingsystem I includes regulating means which is automatically responsive tothe operating condition of the alternator II and varies the excitationof the alternator field I so as to maintain the terminal voltage of thealternator substantially constant regardless of wide variationsoccurring in the speed at which the alternator is driven and in thevalue of the load imposed thereon. This regulating means comprises avoltage regulating unit 35 of the vibratory contact electromagneticrelay type and a current regulating unit or load limitor 36 which isalso of the vibratory contact electromagnetic relay type. The fieldexcitation means for the alternator I I includes a field circuit havingtherein an auxiliary rectifier 3i and a saturable core reactor 33 withwhich the regulator means cooperates for controlling the fieldexcitation.

The field energizing circuit for the alternator Ii comprises a directcurrent portion which includes the field Winding I5 and a pair ofconductors I5a and 52) connecting the ends of the field Winding with thedirect current terminals iii and ll of the field rectifier 3?. The fieldcircuit also comprises an alternating current portion connecting thalternating current terminals 42 and 43 with one phase of the alternatorII, in this instance, the phase represented by the alternator terminalsI61) and IE0. For this purpose the alternating current terminal .2 ofthe field rectifier 3? is connected with the alternator terminal 15b bya conductor i l and the alternating current terminal 33 of the fieldrectifier is connected with the alternator terminal I80 throughconductor means 45 and through the saturable core reactor 38 which willnow be fur ther described.

The saturable core reactor 38 comprises a laminated magnet frame or core45 which, in this instance, has three parallel magnetic circuit legslsa, 63b and 36a. The end legs tiia and 450 carry alternating currentmagnet coils 31 and 58 which are connected in series relation to eachother in th alternating current portion of the field circuit by theconductor means 45. The intermediate leg 56b of the reactor 38 carries adirect current energizing or control winding 49 to which energizingcurrent is supplied under the control of the voltage and currentregulators 35 and 33, as will be presently explained. When the controlwinding 49 is energized by direct current, it produces a magneticcircuit in the core 86 of the reactor 38 which opposes and controls themagnetic flux produced by the alternating current coils 42 and 48 of thefield circuit such that these alternating current coils constituteimpedance coils which will, in turn, control the amount of thealternating current being supplied to the field rectifier 31 inaccordance with the extent of magnetization of th reactor core 43 by thecontrol winding 49.

The voltage regulator 35 comprises a magnet frame 5| including a core 52having a pair of magnet coils 53 and 54 thereon, and a movable armature55 in cooperating relation to the frame and core. The voltage regulator35 also includes a pair of stationary and movable switch contacts 56 and57, of which the latter is carried by the vibratory armatur 55. Atension spring 58 acting on the armature 55 normally urges the movablecontact 51 toward a closed position in engagement with the stationarycontact 56. The coil 53 of the voltage regulator 35 is a voltage coilwhich is connected across the load conductors I8a and I8?) by theconductors 59 and 60 and therefore responds directly to the operatingcondition of the alternator I I and senses the voltage thereof. Aballast resistor 6| may be included in the energizing circuit for themanget coil 53. The magnet coil 53 is a so-called secondary coil whichis in additiv relation to the voltage coil 53 and is adapted to beenergized from the load conductors I8a and I8!) through a circuit whichis controlled by the regulator contacts and will be presently traced.

The current regulator or load limitor 36 comprises a magnet frame 62including a core 53 carrying a load circuit series coil 54 and avibratory armature 65 in cooperating relation to the wmagnetnframe andcore. {iThe current regulator 36 also includes stationary andmovable'switch contacts 66 and 61, of which the latter contact 'iscarried bythevibratory armature 65 and is i normally urged toward aclosed'position in en-. gagement withthe' stationary contactbya tension'spring 68.

" The. voltage and current regulators 35' and-36 are automaticallyresponsiveto the operating condition of the. alternator -ll,=. as:mentioned above, and control. the excitation of Ithafield winding 15 bycontrolling the :energizationof .the

control winding 49 of the saturable1'ireactor-38. In this waythe-contacts of regulators 35' and 36, by controlling relatively smallquantitiesxof. elec-,

vtrical energy which produce changes in the magnetizationjof thecontrolcoil 49, are ableto con- 7 trol. much larger amounts-of alternatingcurrent in the field circuit windings 41 and 48, of

thesaturable reactor and thus produce a strong regulating action; on theexcitation-of the field winding 15 without'subjecting the regulator con-I tacts to harmful arcing. For thiszpurposethe and a voltage divider 10.

The voltage divider comprises a resistor 10a,

' which is connectedacross the direct current load conductors la andI8!) by the conductors H and 12, and a contact arm 19!) which ismanually shiftable along the resistor 10a. The point resistor 69 hasoneaend thereof connected with. .the stationary contact 66 of thecurrent regula- 1tor 36 by a conductor 13 and has its other endconnected with the armature 55, and hence the movable contact 51, ofthevoltage regulator 35 by the conductorumeans 14. Such other end of thepoint resistor 69 is also connected with one end ofthe magnet coil 54 ofthe voltage regulatorby the conductor means 15 and with one end ofthecontrol winding 49 of the saturable reactor 38'.by the conductor 16.The other end of the magnet coil 54 of the voltage regulator isconnected with the-arm 10bof the voltage divider 10 by a conductor 11and the other end of the control coil 49 of the saturable reactor isalso connected with themovable arm of the voltage divider throughaconductor 18.

The stationary contact 56 of the voltage regulator is connected with thearmature .65 of the current regulator by the conductor 19. Y Theenergizing circuit for the magnet coil 54 of the volt- I age regulatormay also include a resistor 80 of suitable value.

In the circuit arrangement just described for coil 54 of the voltageregulator alsoincludes the point resistor 69 whenever'the switchcontacts of either the voltage regulator 35 or'the'current regulator 36are open. When the point'resistor 69 is inserted into the energizingcircuit for the control winding 49 and the magnet coil 54 by the openingof the voltage regulator "or the current regulator contacts, it willproduce a decreased energization of suchwinding and magnet coil tothereby decrease the magnetization of'the core '6 46 of the-saturablereactor and the magnetization of the frame 5| and thecore-52'ofthe-voltage regulator. The effect of this decrease inthemagnetiza- 5tion of the core 46 ot the saturable reactorl 38 :'is to cause adecrease inthe excitation of the field winding [5 and to permitclosingof the contacts 56 and 51 ofthe voltage regulator. When I thepoint resistor 69 is 'short-circuited .outnof 10 this control circuit bythe closing ofithecontacts of the voltage andcurrent regulators,theenergization of the control winding 49 ofathezsatur- Mable reactor 38is increased and theienergiz'ation ofjthe. magnet coil 54 of thevoltagefregulator 35 is. also increased. This increase in thei:ener-"inet' coil'54 causes. 'anxincrease in the .energization. of the.fieldwinding. I 5. and an increased .pull on thearmature 550i thevoltage regulatorto cause opening of the contacts 56 and 51 to therebyreinsert' the point resistor'69 in the control circuit. It will beunderstood, of course; that the opening and closing of the switchcontacts of. the voltage and current regulators takes place at averyrapid vibratoryaction.

'Inithe circuit arrangements and functioning above described, thevoltage divider 10 serves an important purpose because by selecting asettingfor the contact arm 10b such that the voltage applied to theregulatorcontactsfifi, 51 and 66,61 will be low,.harmful sparking or asustained ionization at'thesecontacts willbe prevented.

Fig. 2 of the drawings shows an improvedgenthe above describedgeneratingsystem [9 and functions in a similarmanner but in which the voltageregulator is a' double contact'regulator. Since the various parts of thesystem 82 are similar to the parts of the system H] and function in asimilar manner, the corresponding parts have been designated by the samereference characters,with the exception of the additional pair ofcontacts of the voltage regulator s 35. These additional contactsof thevoltage regulator are a lower pair of contacts comprising a stationarycontact 83' and a movable contact'84 carried by the vibratory armature55. The sta- 'tionary contact 83 is connected with the movable contactarm 10b of the voltage divider10 by the conductor 65. 7

Since the generating system v82 employs .circuits similar to thosedescribedabove for the system l9, and produces an efiective regulationof the excitation of the alternator ll insubstantially the same way andwith minimum destructive sparking at the contacts of the voltage andcurrent regulators 35 and 36, it is not-necessary to repeat the detaileddescription of these circuits and the functioning of the apparatus 60-tacts 83 and 84 of the voltage regulator 35.,addi- 'tional detaileddescription is needed and it is accordingly pointed out that when thecondition of operation of the alternator I l is such that'thefunctioning'of the voltage regulator shifts'from operation on the upperpair of contacts 56 and 51 to operation on the lower pair of contacts 83and 84, the closing of the lower contacts will cstablish a circuit whichsubstantially shortcircuits the control windings 49 of the saturablereactor 38 and the magnet coil 54 of the voltage regulator and, hence,will quickly reduce the en- 'ergization of this control winding and this"regu- "'lator coil substantially to a zero value. This gizationof thecontrol-winding 49and the:mag-' crating system 82 which is generallysimilar to With'respect to the lower pairof switch con- 7 circuit,established by the closing of the lower pair of contacts 83 and 84 andwhich substantially short circuits the control winding 49 and the magnetcoil 54, extends from the load con ductor [8a through the conductor H,then through the left-hand portion of the resistor 10a of the voltagedivider 10, through the contact arm 7017, through the conductor 85,through the lower pair of regulator contacts 83 and 84, the conductormeans 14, and then through the point resistor Be and the conductor 13 tothe load conductor l8b.

. By selecting a setting for the contact arm 10b of the voltage divider'Hl such that the voltage applied to the contacts 83, 84 of the doublecontact regulator 35 will be at or below the critical value forsustained ionization, the danger of burning or welding together of thecontacts by the occurrence of a high short-circuiting current when theregulator operates on the lower pair of contacts is definitelyprevented.

Figs. 3 and i of the drawings show other generating systems 81 and 88which are generally similar to the systems IE] and 82, respectively, butin which the saturable reactor means of the alternator field excitationcircuit is a three-phase saturable reactor. In other respects, thesystems 8? and 88 employ substantially the same circuits and function insubstantially the same manner as the above described systems it! and 82,and the corresponding parts and circuit connections are designated bycorresponding reference characters and without repetition of thedetailed description. With respect to the saturable reactor means of thegenerating systems 87 and 88, it is explained that the three-phasesaturable reactor 89 shown in each of these systems comprises threeindividual saturable reactors 89a, 89b and 890, each of which issubstantially identical with the saturable reactor 38 of the generatingsystem 40 described above. The three individual reactors 89a, 89b and890 are located in the alternating current circuit portions of theenergizing circuit for the alternator field l and one of theseindividual reactors is located in each of the threephase alternatingcurrent circuit portions 90, SI and 92 which connect the alternatingcurrent terminals 53, 94 and 95 of the field rectifier 31 with thealternating current terminals lBa, lBb and IE0 of the alternator.

From the accompanying drawings and the foregoing detailed description itwill now be readily understood that this invention provides generatingsystem control means by which the field excitation of a variable speedvariable load alternator can be eifectively and reliably controlled bythe use of a voltage regulating device of the relay type acting througha saturable reactor located in the alternating current portion of thefield energizing circuit. It will also be seen that the controlexercised on the field circuit and the saturable reactor means containedtherein can be produced, in part, by a voltage regulator and, in part,by a current regulator and also that, if desired, the voltage regulatorcan be of the double contact type and the saturable core reactor meanscan be a three-phase reactor. It will now also be recognized that sincethe regulating action of the voltage and current regulators on the fieldexcitation of the alternator, when accomplished through the saturablereactor means, requires only relatively small voltage and current valuesto be imposed on the vibratory contacts of the regulators and, hence,these contacts will have a long service life. Additionally, it will beseen that this invention provides load relay energizing means for avehicle generating system of this character in which the magnet coil ofthe load relay is energized directly from the alternator through anauxiliary rectifier.

Although the generating system control apparatus of this invention hasbeen illustrated and described herein to a somewhat detailed extent, itwill be understood, of course, that the invention is not to be regardedas being limited correspondingly in scope but includes all changes andmodifications coming within the terms of the claims hereof.

Having thus described my invention, I claim:

1. In an electrical generating system for use on motor vehicles, analternator having a field winding, a main rectifier, an external directcurrent load circuit connected with said alternator through said mainrectifier, a field circuit connected with said alternator and includingan auxiliary rectifier for supplying rectified curent to said fieldwinding, a saturable reactor comprising a core having thereon amagnetizing coil and an impedance coil, said impedance coil beinglocated in the alternating current portion of said field circuit, avoltage regulator of the relay type having magnet coil means responsiveto the operation of said alternator and also having vibratory switchcontact means, a circuit for energization of said magnet coil means andsaid magnetizing coil from said direct current load circuit andcontrolled by said contact means, and a voltage divider in thelast-mentioned circuit for selecting the voltage of the current suppliedto said magnet coil means.

2. In an electrical generating system for use on motor vehicles, analternator having a field winding, a main rectifier, an external directcurrent load circuit connected with said alternator through said mainrectifier, a field circuit connected with said alternator and includingan auxiliary rectifier for supplying rectified current to said fieldwinding, a saturable reactor comprising a core having thereon amagnetizing coil and an impedance coil, said impedance coil beinglocated in the alternating current portion of said field circuit, avoltage regulator of the relay type having magnet coil means responsiveto the operation of said alternator and also having vibratory switchcontact means and a resistor in shunt relation to said contact means, acircuit for energization of said magnet coil means and said magnetizingcoil from said direct current load circuit and controlled by saidcontact means and said resistor, and a voltage divider in thelast-mentioned circuit adapted to permit the selection of a relativelylow value for the voltage applied to said contact means.

3. In an electrical enerating system for use on motor vehicles, analternator having a field winding, a main rectifier, an external directcurrent load circuit connected with said alternator through said mainrectifier, a field circuit connected with said alternator and includingan auxiliary rectifier for supplying rectified current to said fieldwinding, a saturable reactor comprising a core having thereon amagnetizing coil and an impedance coil, said impedance coil beinglocated in the alternating current portion of said field circuit, avoltage regulator of the relay type having a first magnet coil connectedacross said direct current load circuit and a second magnet coil andalso having vibratory switch contact means, and a circuit forener-gization of said magnetizing coil and said second magnet coil fromsaid direct current load circuit and controlled by said contact means.4.'In"an electrical generating :system for use on motor vehicles, analternator having a field winding, a main rectifier, an external directcurrent load circuit connected with said alternator through said mainrectifier, a field circuit condirect current load circuit and asecondm-agnet coil and also having vibratory switch contact means, acircuit for energization of said magnetizing coil and said second"magnet coil from said direct current load circuit and controlled bysaid contact means, and a voltage divider in the last-mentioned circuitfor varying the voltage of 1 the current supplied to said magnetizingcoil and to said second magnet coil and also adapted to permit theselection of a relatively low value for the voltage applied to saidcontact means.

5. In an electrical generating system for use on motor vehicles, an'alternatorhaving a field winding, a main rectifier, an external directourrent load circuit connected with said alternator through said mainrectifier, a field circuit connected with said alternator and includingan 1 auxiliary rectifier for-supplying rectified-current to said fieldwinding, a saturable reactor com,- prising a corehaving thereon amagnetizing coil and 'an'irnpe'dance coil,said impedance coil beinglocated in the alternating current portion of said field circuit, avoltage regulator of the relay type.

having voltage magnet coil means connected across said direct currentload circuit and responrent load circuit and controlled by the switchcontact means of said voltage regulator and by the switch contact meansof said current regulator, and a voltage divider in the last-mentionedcircuit for varying'the voltage of the current supplied-to said magnetcoilmeans and also adapted to permit the selection of a relatively lowvalue for the voltage applied to said contactmeans.

"7. In an electrical generating system for use on .motor vehicles, analternator having a field winding and load terminals, a main rectifier,an

.external :direct current load circuit connected with said loadterminals through said main rectifier, a load relay having a magnet coiland series -switch contacts controlling said load-circuit, said switchcontacts being normally open and adapted to be closed by energization ofsaid magnet coil, regulating means including relay means energized fromsaid load circuit and operably connected with said field Winding forvarying the energization of the latter automatically in response'tochanges in the operating conditions of said alternator, an auxiliaryrectifier, and circuit means connecting said magnet coil with said loadterminals through said auxiliary rectifier for i causing suchenergization of said magnet coil and closing of said series switchcontacts in response to operation of the alternator.

8. In an electrical generating system for use on motor vehicles, athree-phase alternator having a field winding and load terminals, a fullwave three-phase main rectifier, an external direct current load circuitconnected with said load terminals through said main rectifier, a loadrelay having a magnet coil and series switch contacts controlling saidload circuit, said switch contacts being normally open and adapted to besive to the operation of said alternator, said voltage :reg ulator alsocomprising switch contact means adapted to be vibrated by said voltagemagnet coil means, a current regulator of the relay type having acurrent magnet coil in said direct current load circuit and responsiveto the operation of said alternator and switch contact means adapted tobe vibrated by said current magnet coil, and a circuit for energizingsaid magnetizing coil from said direct current load circuit andcontrolled by the switch contact means of said voltage regulator and theswitch contact means of said current regulator.

6. In an electrical generating system for use on motor vehicles, analternator having a field winding, a main rectifier, an external directcurrent load circuit connected with said alternator through said mainrectifier, a field circuit connected with said alternator and includingan auxiliary rectifier for supplying rectified current to said fieldwinding, a saturable reactor comprising a core having thereon amagnetizing coil and an impedance coil, said impedance coil beinglocated in the alternating current portion of said field circuit, avoltage regulator of the relay type having magnet coil means responsiveto the operation of said alternator and switch contact means adapted tobe vibrated by said magnet coil means, a current regulator of the relaytype having a current magnet coil in said load circuit and responsive tothe operation of said alternator and switch contact means adapted to bevibrated by said current magnet coil, a circuit for energizing saidmagnet coil means of said voltage regulator and said magnetizing coilfrom said direct curclosed by energization of said magnet coil,regulating means including relay means energized from said load circuitand operably connected with said field winding for varying theenergization of the latter automatically in response to changes in theoperating conditions of said alternator, a full Wave three-phaseauxiliary rectifier, and circuit means connecting said magnet coil withsaid load terminals through said auxiliary rectifier for causing suchenergization of said magnet coil and closing of said series switchcontacts in response to operation of the alternator.

9. In an electrical generating system for use on motor vehicles, analternator having a field winding, a main rectifier, an external directcurrent load circuit connected with said alternator through said mainrectifier, a field circuit connected with said alternator and includingan auxiliary rectifier for supplying rectified current to said fieldwinding, a saturable reactor comprising a core having thereon amagnetizing coil means and an impedance coil means, said impedance coilmeans being located in the alternating current portion of said fieldcircuit, a first control circuit for energizing said magnetizing coilmeans, a second control circuit adapted to substantially short-circuitsaid magnetizing coil means, and a voltage regulator of the relay typehaving voltage magnet coil means connected across said direct currentload circuit and responsive to the operation of said alternator, saidvoltage regulator also comprising vibratory contact means including onepair of contacts controlling said first control circuit and a secondpair of contacts controlling said second control circuit.

10. In an electrical generating system for use on motor vehicles, analternator having a field winding, a main rectifier, an external directoursubstantially short-circuit said magnetizing coil 1 means, a voltageregulator of the relay type having voltage magnet coil means responsiveto the operation of said alternator and vibratory contact meansincluding one pair of contacts controlling said first control circuitand a second pair of contacts controlling said second control circuit,and a voltage divider connecting said control circuits with said directcurrent load circuit and adapted to permit the selection of a relativelylow value for the voltage applied to the contact means of said voltageregulator.

11. In an electrical generating system for use on motor vehicles, apolyphase alternator having a field winding, a main rectifier, anexternal direct current load circuit connected with said alternatorthrough said main rectifier, a field circuit connected with saidalternator and including an auxiliary rectifier for supplying rectifiedcurrent to said field winding, saturable reactors corresponding innumber with the phases of said alternator and each such reactorcomprising core means having magnetizing and impedance coils thereon,said impedance coils being located in the alternating current portion ofsaid field circuit and connected with the respective phase terminals ofsaid alternator, a first control circuit for energizing said magnetizingcoils, a second control circuit adapted to substantially shortcircuitsaid magnetizing coils, and a voltage regulator of the relay type havingvoltage magnet coil means connected across said direct current loadcircuit and responsive to the operation or" said alternator, saidvoltage regulator also comprising vibratory contact means including onepair of contacts controlling said first control circuit and a secondpair of contacts controlling said second control circuit.

12. In an electrical generating system for use on motor vehicles, apolyphase alternator having a field winding, a main rectifier, anexternal direct current load circuit connected with said alternatorthrough said main rectifier, a field circuit connected with saidalternator and including an auxiliary rectifier for supplying rectifiedcurrent to said field winding, saturable reactors corresponding innumber with the phases of said alternator and each such reactorcomprising core means having magnetizing and impedance coils thereon,said impedance coils being located in the alternating current portion ofsaid field circuit and connected with the respective phase terminals ofsaid alternator, a first control circuit for energizing said magnetizingcoils, a second control circuit adapted to substantially short-circuitsaid magnetizing coils, a voltage regulator or" the relay type havingvoltage magnet coil means connected across said direct current loadcircuit and responsive to the operation of said alternator, said voltageregulator also comprising vibratory contact means including one pair ofcontacts controlling said first control circuit and a second pair ofcontacts controlling said second control circuit, and a voltage dividerconnecting said control circuits with said direct current load circuitand adapted to permit the selection of a relatively low value for thevoltage applied to the contact means of said voltage regulator.

ALBERT D. GILCHRIST.

References Cited in the file of this patent UNITED STATES PATENTSNiunber Name Date 1,710,755 West Apr. 30, 1929 1,788,222 Winter Jan. 6,1939 2,161,179 Logan June 6, 1939 2,374,012 Hanna Apr. 17, 1945

